Tsuda Laboratory
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Spaceflight Mechanics and Exploration Systems Laboratory

Astrodynamics.


本研究室では、宇宙航空力学(宇宙飛行力学)を実際の探査ミッションに応用することに重点を置いて研究を行っています。これには、深宇宙探査衛星や探査機の軌道設計、太陽系探査方法や誘導の研究、宇宙船の航行・制御システムなどが含まれますが、これらに限定されるものではありません。

Hayabusa 2 Mission Design.

Prof. Tsuda and the laboratory have been the main designers for the Hayabusa 2 trajectory and operations. By utilizing a combination of mathematical and engineering techniques, we have studied possible scenarios and Solar System bodies that could become targets for the Hayabusa 2 mission. Using a wide array of techniques, from Porkchop plots to optimization methods taking into account launch and communications windows, the asteroid Ryugu was selected. The members of the laboratory, together with Hayabusa 2 project members and experts in the industry designed the trajectory that took the spacecraft from Earth to the asteroid and back.

Hayabusa 2 planned mission sequence and trajectory.

Hayabusa 2 planned mission sequence and trajectory.

Tsuda Laboratory is also one of the main research centers regarding navigation in the vicinity of small Solar System Bodies. The studies that led to the design of the maneuvers and operations in the vicinity of Ryugu were conducted by the members of the laboratory and close associates. These include, but are not limited to, maneuvering bodies with low gravity, risk assessment studies when navigating such bodies, impact of hazardous debris left over orbiting in the vicinity of the body, and studies of the dynamics involving the depolyment of small landers/rovers on the surface of these bodies.

Another closely related topic to the Hayabusa 2 mission is the capsule reentry studies. Tsuda laboratory has also collaborated in the studies regarding the reentry maneuver, including the design of the trajectory, risk analysis for the capsule's landing, and overall planetary protection considerations.

Novel Space Architecture Concepts.

Moreover, in recent years, different trends in space development are occurring. From one side, there is a push for re-usability and to design systems that enable repeatable access to space. On the other side, there have been numerous one-off missions, as well as closely related missions (Hayabusa and the previosly mentioned Hayabusa 2) to various celestial bodies. With the expansion of these trends and the developing of newer missions (OKEANOS, DESTINY +), the question about a low-cost recurring architecture for deep space exploration missions and its possible benefits has been debated in ISAS and JAXA for some time. Tsuda laboratory is the main proponent behind some new space architectures related to these topics.

Transfer between two orbits of different families.

Transfer between two orbits of different families.

One of the most recent architectures being studied is the so-called Deep Space Orbit Transfer Vehicle (DS-OTV). The Deep Space Orbit Transfer Vehicle (DS-OTV) will be a spacecraft placed in the Earth’s vicinity that will allow exploration missions to rendezvous and dock with it, re-fuel, and continue towards their main objective, including a possible Earth swing-by. This architecture benefits from lower mass at launch for the successive missions, allowing for smaller and lower-cost launchers like the Epsilon or the future H3 to be used, higher availability of launch windows and flexibility against delays and unforeseen circumstances. The design of its parking orbit is crucial, as it needs to be accessible while keeping low stationkeeping costs.

Some early ideas include the usage of Lagrange or Libration point orbits for such a parking orbit, being of special interest the orbits around points L1,2 and the transfers between them, as their topological structure allows for the existence of stable/unstable manifolds emanating from them that can be used for transfer trajectories. Current studies in the laboratory include the generation of these orbit families, the classification, characterization and evaluation of the suitability of the orbits for the DS-OTV purposes. Included in these studies is the design of the transfers between parking and transfer orbits, the optimization of such maneuvers and the conceptualization and design of the rendezvous and docking procedures. In order to tackle this problem, the two spacecraft need to come to the same orbital position at the same time, and the creation and design of a framework that allows this with as much flexibility as possible in regards to the time, fuel consumption and frequency of the maneuver availability is one of the cornerstones of this novel concept.

Deep Space Orbit Transfer Vehicle Sequence Proposal.

Deep Space Orbit Transfer Vehicle Sequence Proposal.

As an applied-focused laboratory, we are also concerned with the holistic view of space mission design. As such, our research always includes studies on the applicability of our ideas and concepts, including the design of whole missions that showcase our findings. This keeps our research grounded in reality and allows for our novel concepts to be iterated quickly and included in real life missions in a short amount of time. This philosophy has been one of the basics tenets of Prof. Tsuda and the laboratory, allowing for the design, construction and operation of some of the most important japanese space missions in history by our members and collaborators.

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